Last week's midterm elections made Republican representatives from wealthy districts an endangered species.
Democrats flipped 10 Republican-held seats among the 50 House districts with the highest household median incomes, a span ranging from $77,468 to $116,069. If Democrat Katie Porter hangs on to an apparent victory over Republican incumbent Mimi Walters in California's 25th District, that would raise the total to 11.
That also would leave just nine Republican representatives in the 50 richest districts — and none in the top 20.
Democrats would have 39. (For purposes of this comparison, we did not count the three districts in Pennsylvania that cracked the top 50 because the data are based on census figures that now are out of date in the Keystone State following a court-ordered redistricting that radically altered the district boundaries).
The trend is not new. For some time, Republicans have found America's toniest ZIP codes hostile territory. President Donald Trump carried just 11 of the top 50 districts — 12 including one of the now-changed Pennsylvania districts.
But the trend appears to be growing stronger.
Democrats now have the richest congressional district in the country, measured by median income — the 10th District in Northern Virginia, where half of households earn more than $116,069. Democrat Jennifer Wexton handily defeated incumbent Republican Barbara Comstock.
Democrats also made inroads in New Jersey. Tom Malinowski and Mike Sherill won districts that narrowly backed Trump in 2016. They rank fifth and seventh, respectively, in household median income.
The Illinois 6th Congressional District in suburban Chicago is home to loads of upscale voters who reliably backed Republicans for decades. It has been in Republican hands since the early 1970s, when it was created after redistricting. The venerable Henry Hyde represented it for 32 years.
But Democrats have become more competitive. Former President Barack Obama won it narrowly in 2008, and Hillary Clinton carried it by 7 percentage points in 2016.
Last week, Republican Peter Roskam — who had been in office since 2006 — went down to defeat.
Republican Rep. Randy Hultgren suffered the same fate in the neighboring 14th District.
The election brought signs of trouble for the GOP in upper-income districts throughout the country. Democrat Harley Rouda defeated Republican Rep. Dana Rohrabacher in a district in once solidly Republican Orange County in California.
Republicans only narrowly survived in a number of other top-50 districts. Republican Young Kim is clinging to a 711-vote lead in California's 39th District in a race that has not yet been called. Reps. Peter King and Lee Zeldin both won single-digit re-election races on New York's Long Island.
A generation ago, it was the GOP that dominated these upper-income suburban enclaves, while the Democrats maintained their House majority through a combination of inner-city districts and large stretches of rural and small-town America.
Following the 1990 election, for instance, Democrats still represented most of the South— but also North Dakota and South Dakota, both congressional districts in Idaho, western Colorado and two of Utah's three districts.
Perhaps no state better illustrates the transformation that has taken place since than Minnesota. Last week, Democrats knocked off two Republicans there in suburban districts outside of Minneapolis.
Democrat Dean Phillips turned out Republican Rep. Erik Paulsen in the 3rd District, where the $81,804 median income is the 36th highest in the country. Angie Craig defeated Rep. Jason Lewis in the 2nd District, which ranks 50th, with a median income of $77,468.
But Minnesota was the rare state where Republicans picked up seats, too. Jim Hagedorn won a race in the 1st District along the southern part of the state to replace a retiring Democrat. Compared to the Minneapolis suburbs, it is decidedly downscale, ranking 174th in median income at $57,780.
The 8th District, which covers the largely rural northeastern corner of the state, was for decades one of the most reliably Democratic areas of the country. Its household median income of $51,684 puts it in the bottom half of the country — 247th.
Except for a single term from 2011 to 2013, the district has been represented by a Democrat since the end of World War II. But Republican Pete Stauber won the open seat last week.
Looking ahead, Democrats appear to have room to grow. Winning Republicans last week won 53 percent of the vote or less in Missouri's 2nd District outside of St. Louis; Ohio's 12th District outside of Columbus; Georgia's 7th District north of Atlanta; the 2nd and 10th Districts in the Houston areas in Texas, and the 24th District in the Dallas-Ft. Worth metropolitan area.
All of those districts rank among the top 100 in household median income.
It will be difficult for Republicans to win national elections if they cannot compete in upscale urban and suburban congressional districts even if they remain dominant in exurban and rural districts.